Warn on incompatible versions of the gateway and other internal packages

The somewhat implicit contract we use during development is that the `@apollo/gateway` package and its dependencies are released together and should be used together. In other words, you shouldn't mix-and-match various versions of, say, `@apollo/gateway` and `@apollo/query-planner` or `@apollo/federation-internals`.

But in practice, this may not be obvious to all users and I wonder if we could maybe do a better job of warning users to not mix-and-match versions of our packages. At a minimum, we could maybe be a bit more explicit about this in the readme of the various packages, but I wonder if the gateway can detect the version in use of those other packages and issue a warning if, say, the minor versions don't match.

Note: creating this because someone run into such a problem of mixing versions and getting an issue in #2392 .

No files, tests, or entry points are named. Start by locating the @apollo/gateway package and its @apollo/query-planner and @apollo/federation-internals dependencies, then determine how version compatibility could be detected and where a warning should appear. Done means an agreed warning behavior for incompatible versions, with package README guidance updated if that is selected.

Written by the indexing model from the issue text.